The invention relates to a system for the marking and identification of objects, particularly work implements such as tools and work piece holders required in manufacturing processes, having modules with an electronically readable marking which are to be arranged on the objects to be marked, and having a testing device with at least one pick-up capable of reading the marking, whereby each module contains at least one oscillating circuit to produce a distinguishing resonance frequency or combination of resonance frequencies.
In known systems developed for marking tools and palettes in fully automatic manufacturing systems, the modules contain a memory, which either is already programmed or can be programmed by the user, such as a common commercial EPROM in which the marking is represented by a selected code. In addition, the module includes contacts which must be engaged by counter-contacts to pick-up and read the marking stored in the memory. When little space is available to house the module, as is often the case with tools, the only option available for receiving the module is a recess in the shaft. Under these circumstances modules are expensive. In addition, establishing the connection between the module and the pick-up is difficult and inhibits work speed and operational reliability. Also, when programmed by the user these modules demand corresponding skills and devices which are often not available and often leave the solution of the module programmed by the manufacturer as the only remaining option. This procedure is expensive and can lead to incorrect markings as a result of the danger of confusion.
It is also known in identifying mobile work piece holders to provide each work piece holder with a module containing one or more electrical oscillating circuits. This module differs from common modules in its resonant frequency or resonant frequency combination. The work piece holders can thus be identified when its module is passed by stationary sensors which detect the resonant frequency or resonant frequency combination. When there is a relatively large number of different objects to be marked, this kind of identification system requires a large expense. In addition, the danger of incorrect correlations in equipping the objects with the different modules is great.